# US 12,216,199 B2 · De-aliased imaging for a synthetic aperture radar > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,199 B2 - Document ID: US12216199B2 - Status: Granted - Kind: B2 - Application number: 17/503,212 - Filed: 2021-10-15 - Published: 2023-01-19 - Granted: 2025-02-04 - Earliest claimed: 2021-07-15 - Assignees: Aptiv Technologies AG - Applicants: Aptiv Technologies AG - Inventors: Le Zheng; Yu Zhang; Edgar Ortiz; Clinton Colby - Web page: https://patentgrep.com/patent/US12216199B2 ## CPC - G01S 13/9027: {Pattern recognition for feature extraction} - G01S 13/931: of land vehicles - B60W 50/06: Improving the dynamic response of the control system, e.g. improving the speed of regulation or avoiding hunting or overshoot - G01S 7/2813: {Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays (specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00)} - G01S 13/9017: {with time domain processing of the SAR signals in azimuth (G01S13/9005 takes precedence)} - G01S 13/9021: {SAR image post-processing techniques} - G06T 5/20: using local operators - G06T 5/70: Denoising; Smoothing - B60W 60/0015: {specially adapted for safety} - B60W 2420/408: Radar; Laser, e.g. lidar - G06T 2207/10044: Radar image - G06T 2207/30252: Vehicle exterior; Vicinity of vehicle - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract This document describes techniques for enabling de-aliased imaging for a synthetic aperture radar. Radar signals processed by a synthetic aperture radar (SAR) system may include false detections in the form of aliasing induced by grating lobes. The techniques described herein can reduce the adverse effects of grating lobes by obtaining an initial SAR image using a back-projection algorithm. Aliasing effects (e.g., false detections) in this initial image may be common due to the limitations of an SAR system moving at non-uniform speeds. A refined image is produced from the initial image by applying a de-aliasing filter to the initial image. The refined image may have reduced or eliminated false detections that attribute to aliasing effects, resulting in a better representation of the environment of the vehicle. ## Claims ### Claim 1 A method of de-aliased imaging for a synthetic aperture radar, the method comprising: identifying, based on multiple frames of signals received by a plurality of receive channels of a radar system, range-Doppler detections corresponding to each receive channel of the plurality of receive channels; applying a back-projection algorithm to the range-Doppler detections identified for each of the receive channels to determine a set of pixels for each respective receive channel, each pixel in each of the sets of pixels indicative of the range-Doppler detections identified at a position corresponding to that pixel; deriving, from each set of pixels, initial images related to each receive channel; applying a de-aliasing filter to the initial images derived from the back-projection algorithm to produce a refined image; and outputting, to a system for controlling a vehicle, the refined image produced by the de-aliasing filter applied to the initial images derived from the back-projection algorithm. ### Claim 2 (depends on 1) The method of claim 1, wherein applying the de-aliasing filter to the initial images comprises: applying, for each of the receive channels, the de-aliasing filter across each pixel in each set of pixels related to each receive channel to produce a set of filtered pixels; and using the set of filtered pixels to produce the refined image. ### Claim 3 (depends on 2) The method of claim 2, wherein using the set of filtered pixels to produce the refined image comprises omitting false detections due to aliasing effects of grating lobes present within the initial images. ### Claim 4 (depends on 2) The method of claim 2, wherein applying, for each of the receive channels, the de-aliasing filter across each pixel in each set of pixels comprises: determining an array steering vector for each pixel in each set of pixels; and filtering, based on the array steering vector for each pixel in each set of pixels, the initial images to produce the refined image. ### Claim 5 (depends on 4) The method of claim 4, wherein determining the array steering vector for each pixel in each set of pixels comprises: determining a horizontal distance between each of the receive channels and a radar center; and determining an azimuth of each pixel in each set of pixels associated with each of the receive channels. ### Claim 6 (depends on 5) The method of claim 5, further comprising: combining a conjugate of the array steering vector and the respective pixel in each set of pixels associated with each of the receive channels to produce the set of filtered pixels. ### Claim 7 (depends on 6) The method of claim 6, further comprising: combining the set of filtered pixels associated with each of the receive channels to produce the refined image. ### Claim 8 (depends on 1) The method of claim 1, further comprising: eliminating, based on applying of the de-aliasing filter, the aliasing effects of the grating lobes. ### Claim 9 (depends on 1) The method of claim 1, further comprising: responsive to reducing the aliasing effects of the grating lobes, representing, at a single position in the refined image, a target that appeared at multiple positions in the initial image. ### Claim 10 (depends on 1) The method of claim 1, wherein the vehicle travels at a non-uniform speed. ### Claim 11 (depends on 1) The method of claim 1, wherein the signals are under-sampled. ### Claim 12 A radar system comprising: at least one processor configured to: identify, based on multiple frames of signals received by a plurality of receive channels of a radar system, range-Doppler detections corresponding to each receive channel of the plurality of receive channels; apply a back-projection algorithm to the range-Doppler detections identified for each of the receive channels to determine a set of pixels for each respective receive channel, each pixel in each of the sets of pixels indicative of the range-Doppler detections identified at a position corresponding to that pixel; derive, from each set of pixels, initial images related to each receive channel; apply a de-aliasing filter to the initial images derived from the back-projection algorithm to produce a refined image; and output, to a system for controlling a vehicle, the refined image produced by the de-aliasing filter applied to the initial images derived from the back-projection algorithm. ### Claim 13 (depends on 12) The radar system of claim 12, wherein the at least one processor is further configured to apply the de-aliasing filter to the initial images by at least: applying, for each of the receive channels, the de-aliasing filter across each pixel in each set of pixels related to each receive channel to produce a set of filtered pixels; and using the set of filtered pixels to produce the refined image. ### Claim 14 (depends on 13) The radar system of claim 13, wherein the at least one processor is further configured to apply the de-aliasing filter by at least: determining an array steering vector for each pixel in each set of pixels for each of the receive channels; combining a conjugate of the array steering vector and the respective pixel in each set of pixels associated with each of the receive channels; and combining the sets of filtered pixels associated with each of the receive channels to produce the refined image. ### Claim 15 A computer-readable storage medium comprising instructions that, when executed, configure at least one processor to: identify, based on multiple frames of signals received by a plurality of receive channels of a radar system, range-Doppler detections corresponding to each receive channel of the plurality of receive channels; apply a back-projection algorithm to the range-Doppler detections identified for each of the receive channels to determine a set of pixels for each respective receive channel, each pixel in each of the sets of pixels indicative of the range-Doppler detections identified at a position corresponding to that pixel; derive, from each set of pixels, initial images related to each receive channel; apply a de-aliasing filter to the initial images derived from the back-projection algorithm to produce a refined image; and output, to a system for controlling a vehicle, the refined image produced by the de-aliasing filter applied to the initial images derived from the back-projection algorithm. ### Claim 16 (depends on 15) The computer-readable storage medium of claim 15, wherein the instructions, when executed, configure the at least one processor to apply the de-aliasing filter by at least: applying, for each of the receive channels, the de-aliasing filter across each pixel in each set of pixels related to each receive channel to produce a set of filtered pixels; and using the set of filtered pixels for each of the receive channels to produce the refined image. ### Claim 17 (depends on 16) The computer-readable storage medium of claim 16, wherein the instructions, when executed, further configure the at least one processor to apply the de-aliasing filter by at least: determining an array steering vector for each pixel in each set of pixels for each of the receive channels; combining a conjugate of the array steering vector and the respective pixel in each set of pixels associated with each of the receive channels; and combining the sets of filtered pixels associated with each of the receive channels to produce the refined image.